Water heater



c M. osTERHELD 2,457,596

WATER HEATER 2 sheets-sheet 1 INVENToR.

De.28,194s.

Fliled Nov. 19;J 1946 3| CLARK M. OSTERHELD BY #ww ,WTV

Dec. 28? 1948. c. M. osTERHELD WATER HEATER 2 sheets-sheet 2 Filed Nov. 19, 1946 I N VEN TOR. CLARK M. OSTERHELD BY ATTY Patented Dec. 28, 1948 uNrTrED 5;.sfrA'rE-s ""WAIER HEATER Clark M. Osterheld; Stoughton, .Wsqassignor to .-MeGraw Electric Company,l u

poration elaware nvAl'splie'a-tion November 19,"1946,;SexlahNos710774 .f My, invention relates. to.-electric .fwaterfrheaters Another object offimyvfinvention: isttrarprovide- "an internal electric waterv heater having amela- 5 Atively large heat radiation surface.

f Another object of my invention-fisxtofsproyide .-faninternal electric Water heater` :usingrintegral .'andinorganic insulation upon not'onlyptheiresistance conductorfbut also uponfthecasing fon-the 1 conductor.

1. `In the drawings,

" .Figure 1 is a view n.:verticalsection through a .domestic hot water tank.emhodyingfan:;internal electric waterheater comprisingmy invention,

.a Fig. 2 is a View mainlyin'front-elevation. with certain parts.' shown in .section, ofi-an electric Ywater heater .embodyingmy invention,

.n Fig; 3.is aview in, section'therethroughgtaken von the line 3+3 of Fig. 2,

Fig. 4 is a View mainly in' -frontelevatiomwith ,@certainparts cut away to show theinternaliconstruction thereof, of a modified form-ofelectric .water heater,

.i `Fig. 5.15 a-.fview-inr lateral section therethrough rta-ken. on; theline 5-.-5 oftFig. 4, and,

` f. .Fig. 6 is a view in section'taken on, thezline'G-f-S i-iof'lFig. 4.

i. Referring rstf. of all to Eig. 1: of the. drawings,

: :I have there shown astandard `domestic iron hot @Water tanky It comprising la lower closureV member I 3, .agcold water .inlet pipe:4 l 5.; as` well'gasf an` upper closure member llgand a hot'watersoutlet-fpipe galli.. I provide also amassfoi heat .insulation 2|, esuch as mineral wool, arounchthe tank Hawhich '1;'. may be held.` in proper operative position .bypan outer casing 23. lprovidelan .electricwater heater designated in its entirety by the numeral 25, this water heater being adapted. to be mounted inside of ...thehot water.. tank Il.

The heater`i25 comprises an .outer tubular casing 21, the inner end of which is closed and the outer endof which is secured vto av plate 29 as by a welding seam 3| therebetween. I providejurther a plate 33 which is secured to therouter. sur- .f .zfaceyoitank l! as by a welding: seam :.35. p It will :.sbe understood that the engaging surfaces: of 1. .f1p1ate233 and of the tankzltzare similarfas -are Lralsoatheengaging surfaces of plates 29-and- 33. Y resistance. .conductori 31; of striprty-pe is riadapted tolse .positioned withinVA the tuber2'l'pthe ,strip '31 f being. helicallye mound fion edge. .YUWhile L haveshown .thexadjacent -convolutionsfof strip .Y .-3't..asbeing;. spaced z; apart lia-doi .not desreetoebe fflimitedtheretofsince with the :construction-#used .-by,me. .in-...thee design-and. the f construction." of, my @improved-electric water heaterthe. adjacent con- @provide a; relatively. velynthinliner 39ffwhich lsnnf. overat-iveengagement `withftheinner surface l0 oi the tube 21, it beingt held; int close: engagement .withirtheinner :surfaceiv of tube 121. :by 'the resistance conductor 31 which is placedazlwithin.1V the tube :12:1 and When-gin,substantiallygaproper:'opera- 1 -f -t1\{e..positiorrtherewithin isallowedutofzexpand.

The, fresistanceizconductor 31, may be ofithexkind used at y present zinzrheostats:Y anda similar =devlices orfv itfvinayf be. an, aluminumza strips; `The #entire .i fouten-surface; of :.the. resistance conductor `31 is .g mrovidedf :with any integral, inorganici, heat-:con-

20,v ducting#highftemperaturefresisting; and f elecftriceinsuiating coating. the thickness of thecoate fing beingf on?. the 1 orden of c2001' rWhile Ihave rstaitedthat: theV .thickness ofthe. .coating is! onthe .gc fordenoffrOOlzztheathiekness ofA saidrcoating may 25 vary from .0005 t0\.0015.f 1v Onemethodofmak- @eine aecoating of this kind is.- set: forthtiriiatent l .#:1526'g121 fi'lhefthirr diner 39l is i also preferably made 1 of w ia1uxninum:.and.=has arthi'cknessron theA ordenof 301.1015Lzalthoughf theA thickness "oi `this"l strip imay 3560i the liner39.. andv -a atVL least theV -inner surface iofntubel are-provided'-fwith Asubstantiallyethe 4--sarne kind'e of coating ashasibeenherenbefore -set forth*- in--connection` --with`A the resistance con- -ductor"31.

40 Lprovide Va'. terminal lead 4| which is...co.nnect.ed

Mutu, wh-ichbolts. areadapted .to .extendthmugh not oply..the.p1ate;29. but alsothrough a clamping replete 49a which. clamping..plate is.. proyidedfwvith man. inner` tubnlarf.- extensionY 5 l v` :which tubular G-.eXtensionrisr-lof such-- lengthfastaengage. a cirt rculanspacere; adaptedt o Aprevent movement; of ithetuuter: .turnsttof conductor 31 .l beyond a .prede- `termined distance.- -N uts; 55.y are provided. ori-each .n ofrthelaoltsxi fand 41, Iwhich .bolts `and *nutsfhold :Mirthe` electric heater 2 5. .1in :watertight .engagement In order to make the amount of heat transmitted from the heater to the water, a minimum per square inch of surface, I provide a l1elically wound fin 51 around the tube 21. This fin may be welded to the outer surface of tube 21.

Referring now to Figs. 4 to 6 inclusive, I have there shown a modified form of electric heater. which heater comprises a tube 6I with its inner end closed, which is substantially of square shape in cross section. I provide liners 63 which are placed against the inside surface of the four sides of tube 6I. The material of the tube 6I is preferably aluminum and the thickness of the wall may be on the order of .095I and may vary between the limits of .03 to .04". The thickness of the liners B3 may be on the order of .015I and may vary between the limits of .01 and .02". The material of the liners is preferably aluminum.

I provide four parallel extending resistance convide three liners 61 between the four resistance conductors.

I provide a plurality of longitudinally extending fins 69, each fin being of substantially L-shape in lateral section and extending over substantially the entire length of the heater. These fins may have a thickness on the order of .015 although I do not desire to be limited to this particular dimension since I may make the thickness of the ns 69 as great as .035". A good conducting connection is provided between each fin 69 with the outer surface of tube 6| so that the fins 69 may receive and transmit a relatively large proportion of heat generated by the resistance conductor 65 within tube 6| to the water.

I provide a terminal lead 1| for the inner end of resistance conductor 65 and I provide a terminal lead 13 for the outer end of resistance con ductor 65. There will thus be provided four terminal leads for the inner ends of resistance conductor 65 as well as four terminal leads for the outer ends and it is possible to connect these in different combinations in order to meet the ree quirements of the supply circuit voltage.

I provide an outer clamping plate 15 having an inner extension 11 thereon which extension 11 is of square shape in lateral section and is adapted to engage a plate 19 which is preferably made of aluminum. Bolts and 41 land nuts 55 are adapted to hold the heater in watertight engagement with the outer surface of the tank Il.

While I may use a resistance conductor material of the kind now generally used I preferably make the resistance conductor 65 of aluminum and make the liners 63 and 61 also of aluminum. I provide the entire outer surface of conductor 65 with an integral, inorganic, heat-conducting, high-temperature-resisting and electric-insulating coating, the thickness of which is on the order of .001", although the thickness thereof may vary from .0005" to .0015. The thickness of the liners 63 and 51 is on the order `of .035" although this dimension may vary between the limits of .03" and .04" and the material is preferably aluminum. I may also provide the entire outer surface of the liners 63 and 61 with substantially the same coat- 4 ing as was hereinbefore set forth as used upon conductor 65. I may also provide substantially the same kind of coating upon the entire inner surface of tube 6I.

The device embodying my invention thus provides an internal electric water heater which can be easily installed and removed from a tank and which in one form thereof is provided with helically wound fins extending from one end of the heater to the other. while the other form thereof is provided with longitudinally extending ns extending substantially the entire length of the heater.

The provision of the hereinbefore described coating of electric insulating material permits of making external dimensions of the tube a minimum and not increasing to too great an extent the amount of heat energy transferred from the tube to the water per square inch of surface.

Various modifications may be made from the device embodying my invention without departing from the spirit and scope thereof and I desire that all such modifications clearly coming within the scope thereof shall be considered a part of my invention.

I claim as my invention:

1. An electric water heater adapted for insertion into a hot water tank comprising a round, tubular, metallic casing having a closed inner end and consisting of a metal having high heat conductivity, a relatively thin metallic liner of high heat conductivity in said casing, a helically wound-on-edge metallic resistance strip adapted to expand its helix when in its operative position inside said liner and casing to hold said liner in close engagement with the inside surface of said casing and a metallic fin secured to the outside surface of said casing and extending helically therealong, said fin consisting of metal of high heat conductivity, said resistance strip and said liner having thereon an integral, inorganic, heatconducting, high-temperature-resisting and electricinsulating coating.

2. An electric water heater adapted for insertion into a hot water tank comprising a thin aluminum casing substantially square in cross section and having a closed inner end, a plurality of relatively thin aluminum liners in said casing, a plurality of aluminum resistor strips within said liners and casing bent to provide a plurality of transversely-extending end-connected convolutions, relatively thin aluminum liners between adjacent resistor strips and aluminum fins secured to the outside of said casing and extending longitudinally thereof, said resistor strips and said liners each having on their outer surfaces an integral, inorganic, heat-conducting, hightemperature resisting and electric insulating coating.

CLARK M. OSTERHELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,117,240 Presser Nov. 17, 1914 1,464,255 Zimmermann Aug. 7, 1923 1,669,385 Wiegand et al May 8, 1928 1,889,445 Lightfoot Nov. 29, 1932 1,996,625 Pendleton Apr. 2, 1935 1,997,844 Wiegand Apr. 16, 1935 2,357,906 Osterheld Sept. 12, 1944 2,372,150 Whittaker Mar. 20, 1945 

